After television stations switch over to digital signals Friday, TV watchers might have to scan for channels on their digital converter box.

At 12:55 p.m. Friday, WRAL-TV will switch from frequency 53 to 48 but stay on channel 5. Those frequencies are in the background, but the change might confuse a converter box.

If that happens, you need to scan channels on the box.

Take the remote control for either your converter box or digital TV. Press the menu, set-up or similarly labeled button.

Use the arrows to perform a channel scan or scan or auto-tone. Your TV might use a different term. The TV will then search for available digital broadcast channels.

It takes about a minute to complete the scan, giving you all the digital channels in the area.

Alternatively, you can unplug the TV for about five minutes and then plug it back in. Most TVs will automatically scan for channels.

A survey of  more than a dozen retailers, including Target and Wal-Mart, showed that all but one had plenty of converter boxers for sale. No store was sold out.